1
STROBE Statement—checklist of items that should be included in reports of observational studies
Item No
Recommendation
Location in manuscript Title and abstract 1 (a) Indicate the study’s design with a commonly used term in
the title or the abstract
Title
(b) Provide in the abstract an informative and balanced summary of what was done and what was found
Abstract
Introduction
Background/rationale 2 Explain the scientific background and rationale for the investigation being reported
Intro
Objectives 3 State specific objectives, including any prespecified hypotheses
Intro
Methods
Study design 4 Present key elements of study design early in the paper Methods/
Design Setting 5 Describe the setting, locations, and relevant dates, including
periods of recruitment, exposure, follow-up, and data collection
Methods/
Participants
Participants 6 (a) Cohort study—Give the eligibility criteria, and the sources and methods of selection of participants. Describe methods of follow-up
Case-control study—Give the eligibility criteria, and the sources and methods of case ascertainment and control selection. Give the rationale for the choice of cases and controls
Cross-sectional study—Give the eligibility criteria, and the sources and methods of selection of participants
Methods/
Participants (b) Cohort study—For matched studies, give matching criteria
and number of exposed and unexposed
Case-control study—For matched studies, give matching criteria and the number of controls per case
Variables 7 Clearly define all outcomes, exposures, predictors, potential confounders, and effect modifiers. Give diagnostic criteria, if applicable
Methods/
Data collect. &
analysis Data sources/
measurement
8* For each variable of interest, give sources of data and details of methods of assessment (measurement). Describe
comparability of assessment methods if there is more than one group
Methods/
Ext. arrang. &
Ext. procedures
Bias 9 Describe any efforts to address potential sources of bias Methods/Design &
Ext. procedures Study size 10 Explain how the study size was arrived at Methods/Statistical
analysis Quantitative variables 11 Explain how quantitative variables were handled in the
analyses. If applicable, describe which groupings were chosen and why
Methods/Data collection & analysis
Statistical methods 12 (a) Describe all statistical methods, including those used to Methods/Statistical
2
control for confounding analysis
(b) Describe any methods used to examine subgroups and interactions
N/A
(c) Explain how missing data were addressed Results/Participants (d) Cohort study—If applicable, explain how loss to follow-up
was addressed
Case-control study—If applicable, explain how matching of cases and controls was addressed
Cross-sectional study—If applicable, describe analytical methods taking account of sampling strategy
N/A
(e) Describe any sensitivity analyses N/A
Continued on next page
3 Results
Participants 13* (a) Report numbers of individuals at each stage of study—eg numbers potentially eligible, examined for eligibility, confirmed eligible, included in the study, completing follow-up, and analysed
Results/
Participants
(b) Give reasons for non-participation at each stage Results/
Participants
(c) Consider use of a flow diagram Figure 4
Descriptive data
14* (a) Give characteristics of study participants (eg demographic, clinical, social) and information on exposures and potential confounders
Table 1
(b) Indicate number of participants with missing data for each variable of interest
N/A
(c) Cohort study—Summarise follow-up time (eg, average and total amount) Outcome data 15* Cohort study—Report numbers of outcome events or summary measures
over time
Case-control study—Report numbers in each exposure category, or summary measures of exposure
Cross-sectional study—Report numbers of outcome events or summary measures
Table 1
Main results 16 (a) Give unadjusted estimates and, if applicable, confounder-adjusted estimates and their precision (eg, 95% confidence interval). Make clear which confounders were adjusted for and why they were included
Results/
Primary outcomes/
Figure 5 (b) Report category boundaries when continuous variables were categorized N/A (c) If relevant, consider translating estimates of relative risk into absolute
risk for a meaningful time period
N/A
Other analyses 17 Report other analyses done—eg analyses of subgroups and interactions, and sensitivity analyses
Results/
Secondary Outcomes Discussion
Key results 18 Summarise key results with reference to study objectives Discussion Limitations 19 Discuss limitations of the study, taking into account sources of potential bias
or imprecision. Discuss both direction and magnitude of any potential bias
Discussion/
Limitations Interpretation 20 Give a cautious overall interpretation of results considering objectives,
limitations, multiplicity of analyses, results from similar studies, and other relevant evidence
Discussion/
Increased act.
of quad.
Generalisability 21 Discuss the generalisability (external validity) of the study results Discussion/
Clinical Impl.
Other information
Funding 22 Give the source of funding and the role of the funders for the present study and, if applicable, for the original study on which the present article is based
Title Page
*Give information separately for cases and controls in case-control studies and, if applicable, for exposed and unexposed groups in cohort and cross-sectional studies.
